Vented Dryer With Modular Heat Pump Subassembly

ABSTRACT

A vented tumble laundry dryer is provided with a heat pump subassembly configured to join with a heater inlet and a blower outlet in an open air flow circuit. The heat pump subassembly forms a closed refrigerant loop. Condenser and evaporator heat exchangers of the subassembly form parts of the open air flow circuit. Air drawn from inside the dryer cabinet passes sequentially through the condenser heat exchanger, the heater, the dryer drum, the process air fan, and the evaporator heat exchanger before being vented to the outside. The heat exchangers have a modular construction that permits one to be stacked on the other and to be angularly offset with respect to the other in both horizontal and vertical planes, thus facilitating integration of the heat pump subassembly into existing vented dryer designs.

FIELD OF THE INVENTION

The present invention relates generally to laundry dryers. In particular, the invention concerns a vented laundry dryer with a heat pump subassembly.

BACKGROUND OF THE INVENTION

Energy efficiency is an important aspect of a dryer, and improved heat recovery offers a valuable tool to improve overall energy efficiency. Conventionally, laundry dryers have existed as either a vented tumble dryer or a condenser dryer.

During operation, a conventional vented tumble dryer draws air from the surrounding area, heats it, and directs it into the drum of the dryer. The dryer then exhausts the air and retained water vapor through a duct to the outside. As shown in FIGS. 1-3, a known vented dryer 10 generally includes a rotatable drum 12; an air supply duct 14 which introduces air from within the dryer housing or cabinet 16 into the drum 12; a heater 18 supplied at a heater tube portion of the air supply duct 14, which heats the air introduced into the air supply duct 14; and an air exhaust duct 20 to exhaust hot air and water vapor from the dryer, typically to a duct that exhausts the air to the outside of the house or other building in which the dryer is located. A fan or blower 22 is provided downstream of the drum 12 for drawing the air through the system and out the exhaust duct 20. A filter 24 for collecting lint and other debris in the air is placed between the drum 12 and the exhaust duct 20. In such a vented tumble dryer 10, the sole heat source is the heater 18 upstream of the drum 12. Moreover, the only heat recovery that takes place is a slight warming of the air drawn into the cabinet 16 before it is drawn into heater 18, by virtue of the heat in the cabinet 16 generated by continued operation of the dryer 10.

A heat pump has been popularly used in condenser dryers. See, e.g., US 2011/0265523. In a typical condenser dryer utilizing a heat pump, the dryer includes a closed air stream circuit and a closed coolant circuit. The air and coolant circuits are coupled by two coolant-air heat exchangers, one associated with a condenser and one associated with an evaporator. The coolant circuit also includes a coolant fluid expansion device and a coolant fluid compressor. Heat is absorbed by the coolant as it is evaporated (at least partially) to the gaseous state in the evaporator. By the evaporator heat exchanger, air exhausted from the dryer drum can be cooled before being recirculated, to thus condense moisture from the air. At the same time, heat of the warm exhaust air improves the efficiency of the heat pump by transferring its heat to the coolant to enhance the coolant evaporation in the evaporator. On the other hand, heat is released by the coolant as it is condensed (at least partially) to the liquid state in the condenser. By the condenser heat exchanger, low moisture air to be re-input to the dryer drum can be re-heated to facilitate the load drying effectiveness thereof. At the same time, that air has a cooling effect on the coolant in the condenser, to thus enhance the efficiency of the coolant condensation process.

Unlike vented dryers which exhaust the warm process air to the outside, condenser dryers continuously recirculate the air exhausted from the drum; they utilize a heat pump (or air-to-air heat exchangers) to condense moisture from the exhausted air, and to facilitate heat transfer to and from the process air. Although condenser dryers generally do not dry as rapidly as vented dryers, they offer a viable approach for applications where it is impossible or impractical to vent the hot moist air to the atmosphere. However, in a closed circuit system, the air in the evaporator exchanges both latent and sensible heat, which effectively decreases overall heat exchange. Moreover, the components of a heat pump system require additional space inside the cabinet of the dryer that can cause cumbersome and costly modifications to more conventional components and designs.

The use of a heat pump in a vented dryer to improve the energy efficiency of the vented dryer has been proposed. See, e.g., US2010/0011608, WO2010/090411. However, these prior proposals have not adequately addressed the practical problems of integration and expense that can impede a successful implementation of a heat pump in a vented dryer. For example, US2010/0011608 incorporates a heat pump in a vented dryer system, but does not address how to make use of the heat pump in conjunction with a conventional gas or electric resistance heater of the dryer. Moreover, dryer efficiency is reduced because the pathway of air through the evaporator heat exchanger, before the exhaust, is highly restricted and with sharp (e.g., 90°) turns. Thus, there remains a need for an effective heat pump system that may fit and effectively operate within a known vented dryer design with little modification to existing structure, to effectively utilize coolant-air heat exchange to further improve dryer efficiency.

SUMMARY OF SELECTED INVENTIVE ASPECTS

It is an object of the present invention to provide a vented tumble dryer with an integrated heat pump system, which overcomes problems as mentioned above, and allows a simple, economical, efficient, and practical installation of the heat pump system within the dryer to improve heat recovery and energy efficiency.

The heat pump system includes a closed circuit refrigerant loop and an open, or vented, air stream circuit. The heat pump subassembly has a condenser heat exchanger, an evaporator heat exchanger, a compressor, and an expansion device joined together by refrigerant tubing/conduit to form a closed loop refrigerant circuit.

The refrigerant circuit is thermally coupled to the air stream circuit at the condenser and evaporator heat exchangers. The air flow circuit of the present invention is open, or vented, so air passes through the air circuit before being exhausted from the dryer cabinet to the atmosphere, similar to the air flow in a conventional vented dryer. However, the air circuit according to aspects of this invention includes the condenser and evaporator heat exchangers of the heat pump, in addition to the conventional heater tube, manifold, drum, and process air fan. As compared to a recirculating condensing dryer, the open loop (vented) air-flow of the heat pump system minimizes undesirable sensible cooling, i.e., an inefficient drop in the temperature of the air before it is heated and passed into the drum.

According to another aspect of this disclosure, the heat pump vented dryer design allows the condenser and evaporator heat exchanger core assemblies (i.e., tubing convolutions and associated heat exchanger fins) to be configured identically. Unlike conventional heat pump dryers where the condenser is generally necessarily larger than the evaporator, the ability to use same sized and configured core assemblies can reduce cost and complexity in manufacturing.

According to an aspect of the invention, the condenser and evaporator heat exchangers of the heat pump subassembly are arranged in a vertically stacked configuration, wherein the condenser heat exchanger is seated on top of the evaporator heat exchanger. The stacked heat exchangers may also be angularly offset. For example, the heat exchangers may be angularly offset from each other in a vertical, horizontal, vertical and horizontal, or other planes (i.e., canted and inclined). As a result, the heat exchangers are arranged in non-parallel relation in at least one plane. As another example, the stacked heat exchangers may be arranged in parallel relation to each other in at least one plane but both angled with respect to another plane (e.g., both angled or angularly offset with respect to a horizontal plane or both angularly offset from a vertical plane). The stacked, angularly offset configuration reduces pressure drops and allows the heat pump subassembly components to more efficiently fit within the traditional vented dryer and connect with traditional dryer components (e.g., exhaust passage) with little modification to standard components (e.g., manifold). The stacked and angled configuration also increases efficiency and decreases pressure drops by avoiding a sharp (e.g., 90 degree) turn for the airflow entering the manifold upstream of the drum.

According to another aspect of this disclosure, the external casings of the condenser and evaporator heat exchanger units are formed from mating casing pieces. For example, in some embodiments, the external casings are formed from three mating pieces. There, the first and second casing pieces mate together to enclose the condenser heat exchanger core assembly and create a passage that directs air through the assembly toward the manifold and drum. The second casing piece also mates together with the third casing piece to enclose the evaporator heat exchanger core assembly and create a passage that directs air through the assembly and toward the air exhaust passage. In other embodiments, the external casings of the condenser and evaporator heat exchanger units are each formed of a pair of mating clamshell pieces (four main pieces). There, each heat exchanger has a top and bottom casing portion mated together to enclose the respective heat exchanger core assembly and create a passage that directs the air through the assembly.

The heat exchanger casings may further include at least one support. The support component or components can support the condenser as it sits at an incline on top of the evaporator, and can further maintain the angular offset, spacing, and position of the heat exchanger units. The supports may be separate from the casing pieces or may be integral to one or more piece of the casing. For example, in the four piece casing design discussed above, the evaporator heat exchanger's top casing piece may include support pieces that mate with support pieces formed in or on the condenser heat exchanger's lower casing piece.

The casing pieces may also include support pieces for mounting or attaching other elements within the dryer cabinet. For example, in some embodiments, one or more casing piece may include a support for a cooling fan that mounts outside the heat exchanger casings near the compressor. One or more casing piece may also include integral supports for the expansion device, refrigerant tubes, or other elements of the heat pump.

Another aspect of this disclosure concerns the collection within and/or expelling of condensate from, the dryer cabinet. The heat pump system includes a reservoir to collect condensed water formed within the evaporator heat exchanger. In an embodiment, the water collection reservoir, or tray, is integrated directly into the bottom or lower casing portion of the evaporator heat exchanger unit.

The heat pump subassembly may also include a water condensate pump for removing water from the reservoir to outside the dryer cabinet or to a removable container inside the cabinet.

According to another aspect of the invention, the dryer with a heat pump assembly may utilize a heater in addition to the heat pump condenser for heating the drying air flow before it is admitted to the drum. For example, a traditional electric heater tube may be paired with the heat pump so the condenser heat exchanger will act as a pre-heater for incoming supply air. The combination of an electric heater with the heat pump can reduce overall drying time and reduce the required size of the heat pump components. Moreover, the use of a second heater can limit the necessary air flow rate, improve performance, and avoid the need for significant modification to the fan or blower of an existing dryer design.

Another aim of aspects of the present invention is to provide a modular heat pump subassembly that can be easily integrated within conventional vented dryers, including at the point of manufacture or as a post-production improvement. Moreover, the components could constitute a kit for retrofitting an existing vented dryer.

Another aim of aspects of the present invention is to provide a vented laundry dryer comprising:

-   -   a drying chamber;     -   a process air fan downstream of the drying chamber for drawing         air through the drying chamber; and     -   a heat pump system comprising a condenser heat exchanger unit         enclosed by separately formed and mated together first and         second casing portions and an evaporator heat exchanger unit         enclosed by the second casing portion mated together with a         separately formed third casing portion;     -   wherein the condenser and evaporator heat exchanger units are         stacked one on top of the other, said condenser heat exchanger         unit connecting to a manifold upstream the drying chamber so         that process air is drawn through the condenser heat exchanger         unit before entering said drying chamber, and said evaporator         heat exchanger unit connecting to an air outlet of said process         air fan so that process air is passed through the evaporator         heat exchanger unit before being exhausted from the dryer; and     -   wherein the heat pump system further comprises a coolant circuit         comprising a coolant fluid expansion device and a compressor.

This vented laundry dryer may further comprise other features. For example, according to aspects of the present invention, the vented laundry dryer may further comprise a heater positioned upstream of the manifold for heating air passing therethrough, said condenser heat exchanger unit connecting to an air inlet of said heater.

Another aspect of the present invention may provide the vented laundry dryer wherein the third casing portion is at least in part below the evaporator heat exchanger unit and further comprises a water condensate reservoir.

According to other aspects of the present invention, the vented laundry dryer may further comprise a water pump arranged to expel water condensate from said reservoir.

Another aspect of the present invention may provide the vented laundry dryer wherein the condenser and evaporator heat exchanger units comprise substantially identical heat exchanger core assemblies.

Another aspect of the present invention may provide the vented laundry dryer wherein the heat exchanger core assemblies each have a generally rectangular box shape.

Another aspect of the present invention may provide the vented laundry dryer wherein the condenser heat exchanger unit is angularly offset with respect to the evaporator heat exchanger unit.

Another aspect of the present invention may provide the vented laundry dryer wherein the condenser heat exchanger unit is angularly offset with respect to the evaporator heat exchanger unit in a horizontal plane.

Another aspect of the present invention may provide the vented laundry dryer wherein the condenser heat exchanger unit is angularly offset with respect to the evaporator heat exchanger unit in a vertical plane.

Another aspect of the present invention may provide the vented laundry dryer wherein the condenser and evaporator heat exchanger units are angularly offset relative to each other in both a horizontal plane and a vertical plane.

Another aspect of the present invention may provide the vented laundry dryer wherein the condenser and evaporator heat exchanger units are attached to each other in parallel in a plane angularly offset with respect to a vertical plane.

According to another aspect of the present invention, the vented laundry dryer may further comprise at least one support structure serving to attach a portion of the coolant circuit to one of the first, second, or third casing portions.

According to another aspect of the present invention, the vented laundry dryer may further comprise a cooling fan for the compressor, wherein the cooling fan is attached to at least one of the first, second, or third casing portions by an intermediate support structure.

Another aspect of the present invention may provide the vented laundry dryer wherein the second and third casing portions form an inlet configured to connect to the outlet of the process air fan.

Another aim of aspects of the present invention is to provide a heat pump subassembly for a dryer with a process air fan, and a drum, the heat pump subassembly comprising:

-   -   a condenser heat exchanger unit having an air inlet and outlet;         and     -   an evaporator heat exchanger unit having an air inlet and         outlet;     -   wherein said condenser heat exchanger unit comprises a condenser         heat exchanger core assembly enclosed in a first casing portion         and a second casing portion, and wherein the evaporator heat         exchanger unit comprises an evaporator heat exchanger core         assembly enclosed by the second casing portion and a third         casing portion; and     -   wherein the first, second, and third casing portions are         configured to stack the condenser and evaporator heat exchanger         core assemblies one on top of the other.

Another aspect of the present invention may provide the heat pump subassembly wherein wherein the first, second, and third casing portions are configured to orient the condenser and evaporator heat exchanger core assemblies in an angularly offset relation

According to another aspect of the present invention, the heat pump subassembly may further comprise a heater, wherein the air outlet of the condenser heat exchanger unit is adapted for connection to an inlet of said heater.

Another aspect of the present invention may provide the heat pump subassembly wherein each of said first, second, and third casing portions comprise separately formed sections.

Another aspect may provide the heat pump subassembly wherein the first and second casing portions are mated together, and the second and third portions are mated together.

Another aspect of the present invention may provide the heat pump subassembly wherein the third casing portion further comprises a condensate reservoir. According to another aspect of the present invention, the heat pump subassembly may further comprise a water pump arranged to expel water condensate from the reservoir.

According to another aspect of the present invention, the heat pump subassembly may further comprise an expansion device, wherein at least part of the expansion device is supported within the dryer by a support component attached to at least one of the first, second, or third casing portions.

Another aspect of the present invention may provide the heat pump subassembly wherein at least a portion of the support component is formed integral with one of the first, second, or third casing portions.

According to another aspect of the present invention, the heat pump subassembly may further comprise:

-   -   a compressor;     -   a cooling fan for said compressor; and     -   at least one support component, wherein at least part of the         cooling fan is supported by the support component and wherein         the support component attaches the cooling fan to at least one         of the first, second, or third casing portions.

Another aspect of the present invention may provide the heat pump subassembly wherein at least a portion of the support component is formed integral with one of the first, second, or third casing portions.

Another aim of aspects of the present invention is to provide a modular heat pump unit for a vented laundry dryer comprising:

-   -   a condenser heat exchanger having an air outlet configured to         join with an air inlet of a heater of the laundry dryer wherein         the condenser heat exchanger comprises a condenser core heat         exchanger assembly enclosed by separately formed and mated         together first and second case portions; and     -   an evaporator heat exchanger having an air inlet configured to         join with an air outlet of a blower of the laundry dryer wherein         the evaporator heat exchanger comprises an evaporator core heat         exchanger assembly enclosed by the second case portion mated         together with a separately formed third case portion;     -   wherein the condenser heat exchanger is attached to and arranged         above the evaporator heat exchanger.

Another aspect of the present invention may provide the modular heat pump wherein the two heat exchangers are angularly offset with respect to each other in both a horizontal and a vertical plane

Another aspect of the present invention may provide the modular heat pump wherein in an installation orientation, the outlet of the condenser heat exchanger is at a greater height than the inlet of the evaporator heat exchanger.

Another aspect of the present invention may provide the modular heat pump wherein the third case portion further comprises a condensate reservoir.

According to another aspect of the present invention, the modular heat pump may further comprise at least one support structure to attach an expansion device to one of the first, second, or third case portions.

Another aim of aspects of the present invention is to provide a modular heat pump unit for a vented laundry dryer comprising:

-   -   a condenser heat exchanger having an air outlet configured to         join with an air inlet of a heater of the laundry dryer wherein         the condenser heat exchanger comprises a first case having         separately formed and mated together first and second case         portions; and     -   an evaporator heat exchanger having an air inlet configured to         join with an air outlet of a blower of the laundry dryer wherein         the evaporator heat exchanger comprises a second case having         separately formed and mated together first and second case         portions;     -   wherein the condenser heat exchanger is attached to and arranged         above the evaporator heat exchanger.

Another aspect of the present invention may provide the modular heat pump unit wherein the two heat exchangers are angularly offset with respect to each other in at least one plane.

Another aspect of the present invention may provide the modular heat pump unit wherein the second case portion of the second case further comprises a condensate reservoir.

According to another aspect of the present invention, the modular heat pump unit may further comprise at least one intermediate support component between the first case and the second case, wherein at least part of the condenser heat exchanger is supported on the second case by the intermediate support component.

Another aim of aspects of the present invention is to provide a vented laundry dryer comprising:

-   -   a drying chamber;     -   a process air fan downstream of the drying chamber for drawing         air through the heater and the drying chamber; and     -   a heat pump system comprising a condenser heat exchanger unit         enclosed by separately formed and mated together first and         second casing portions and an evaporator heat exchanger unit         enclosed by the second casing portion mated together with a         separately formed third casing portion; and     -   wherein the condenser and evaporator heat exchanger units are         stacked one on top of the other and angularly offset from one         another, said condenser heat exchanger unit connecting to a         manifold upstream the drying chamber so that process air is         drawn through the condenser heat exchanger unit before entering         said drying chamber, and said evaporator heat exchanger unit         connecting to an air outlet of said process air fan so that         process air is passed through the evaporator heat exchanger unit         before being exhausted from the dryer.

The above and other objects, features, and advantages of the present invention will be readily apparent and fully understood from the following detailed description of preferred embodiments, taken in connection with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows a side perspective view of a conventional vented tumble dryer, with a portion of the dryer housing removed to illustrate internal components related to aspects of this invention.

FIG. 2 shows a bottom-front perspective view of the conventional dryer shown in FIG. 1, with cabinet panels removed to reveal internal operating and air flow components.

FIG. 3 shows a front perspective view of a dryer basement portion, including the primary internal air flow components of the conventional dryer shown in FIG. 1.

FIG. 4 shows a side perspective view of a vented tumble dryer with a heat pump subassembly with a three piece casing according to aspects of the present invention, with a portion of the dryer housing removed to illustrate internal components related to aspects of this invention.

FIG. 5 shows a side perspective view of the laundry dryer of FIG. 4, with a portion of the dryer cabinet housing, and the dryer drum, removed to illustrate internal components related to aspects of this invention.

FIG. 6 shows a side perspective view of the laundry dryer of FIG. 4, with a portion of the dryer cabinet housing, and the dryer drum, removed to illustrate internal components related to aspects of this invention.

FIG. 7 shows a rear perspective view of a dryer basement portion of the dryer of FIG. 4, including the primary heat pump system components related to aspects of this invention.

FIG. 8 illustrates a top plan view of the dryer basement portion of FIG. 7, including the primary heat pump subassembly components related to aspects of this invention.

FIG. 9 shows a side plan view of the dryer basement portion of FIG. 7, including the primary heat pump subassembly components related to aspects of this invention.

FIG. 10 shows a rear plan view of the dryer basement portion of FIG. 7, including the primary heat pump subassembly components related to aspects of this invention.

FIG. 11 illustrates a front perspective view of the dryer basement portion of FIG. 7, including the primary heat pump subassembly components related to aspects of this invention.

FIG. 12 is a partial side perspective view of the dryer basement portion of FIG. 9, showing aspects of the primary heat pump components and coolant tubes.

FIG. 13 shows an exploded view of selected heat pump subassembly components of the dryer of FIG. 4, including the casings of the first and second heat exchangers.

FIG. 14 shows a side perspective view of a further embodiment of a vented tumble dryer with a heat pump subassembly with a four piece casing according to aspects of the present invention, with a portion of the dryer housing removed to illustrate internal components related to aspects of this invention.

FIG. 15 shows a rear perspective view of a dryer basement portion of the dryer of FIG. 14, including the primary heat pump system components related to aspects of this invention.

FIG. 16 illustrates a top plan view of the dryer basement portion of FIG. 15, including the primary heat pump subassembly components related to aspects of this invention.

FIG. 17 illustrates a side plan view of the dryer basement portion of FIG. 15, including the primary heat pump subassembly components related to aspects of this invention.

FIG. 18 shows an exploded view of selected heat pump subassembly components of the dryer of FIG. 14, including the casings of the first and second heat exchangers.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIGS. 4-13 illustrate a first exemplary embodiment of vented tumble dryer 100 provided with a heat pump subassembly 150. The dryer 100 comprises a cabinet 104 with side walls, a top wall, and a bottom basement frame. The dryer 100 further comprises a rotating drum 102, process air fan 108, and heater tube 106 which may comprise multiple heating elements. The dryer 100 also includes, in a conventional fashion, a lint filter 112 (FIGS. 5-10) provided between the drum 102 and the blower 108. The dryer 100 may also include other elements traditionally known in a vented dryer (e.g., motor 116 in FIGS. 5-8).

As seen in, e.g., FIG. 7, the heat pump subassembly 150 of the laundry dryer 100 includes a compressor 152, condenser heat exchanger 154, expansion device 156, evaporator heat exchanger 158, and refrigerant tubing/conduits 160. The condenser and evaporator heat exchangers 154 and 158 thermally couple two circuits: a closed loop refrigerant circuit and an open or vented air stream circuit.

The compressor 152, condenser heat exchanger 154, expansion device 156, and evaporator heat exchanger 158 are connected via refrigerant tubes/conduits 160 (see, e.g., FIGS. 7 and 12) to form a closed loop heat pump refrigerant circuit. Condenser heat exchanger 154 is associated with a refrigerant condenser on the high pressure side of the heat pump system 150 between the outlet of the compressor 152 and the inlet of the expansion means 156. Evaporator heat exchanger 158 is associated with a refrigerant evaporator on the low pressure side of the heat pump system 150 between the outlet of the expansion means 156 and the inlet of the compressor 152. It is to be noted that herein, the terms “condenser” and “evaporator” are used in the conventional sense to refer to apparatus which at least partially condense and evaporate refrigerant, respectively. These terms should not be taken to require a full state change of the refrigerant at the different stages. In other words, it is contemplated that the refrigerant may remain partially in the liquid state in the evaporator, and remain partially in the gaseous/vapor state in the condenser. For example, if CO2 is used as a refrigerant, a gas cooling process occurs and there is no phase change in the condenser, but depending on conditions a phase change likely occurs in the evaporator from a mixed vapor/liquid state to a full vapor state. For other refrigerants, a full phase change may occur in both the condenser and evaporator, with the refrigerant passing from a vapor state through a liquid state in the condenser, and the refrigerant passing through a mixed liquid/vapor status to a full vapor state in the evaporator.

The refrigerant is compressed by the compressor 152. The compressor sucks or pulls in low pressure and low temperature refrigerant and discharges the refrigerant in a high temperature and high pressure vapor state, thus resulting in warming of the refrigerant and the tubing carrying the same. The now pressurized and heated refrigerant then flows in the refrigerant tubes 160 through the condenser heat exchanger 154. In the condenser heat exchanger 154, the warm refrigerant transfers heat to the entering ambient air stream, via the heat exchanger fins or the like, thereby warming the air stream. At the same time, the cooling effect of the air on the refrigerant allows the refrigerant condensation. The refrigerant then travels through refrigerant tubes 160 to expansion device 156 provided between the condenser 154 and evaporator 158. The expansion device 156 may, for example, be a capillary tube (see, e.g., FIGS. 7-10 and 12), expansion valve, or other means known in the art to lower the pressure of the refrigerant. A change of state of at least some of the refrigerant to the gaseous state due to the pressure decrease results in an absorption of heat energy, thus resulting in cooling of the refrigerant. The refrigerant then continues toward the evaporator heat exchanger 158. In the evaporator heat exchanger 158, the warm air exiting the drum 102/fan 108 transfers heat energy to the cooled refrigerant, and the air is thus cooled, while the efficiency of the evaporation process is increased due to the heat recovery from the warm exhaust air. The refrigerant then loops back to the compressor 152 and continues along the closed loop heat pump circuit.

Unlike a recirculation condenser dryer, the air flow circuit in the illustrated embodiment is an open or vented circuit. When the heat pump subassembly 150 is installed in the dryer 100, it is fitted between the inlet of the heater tube 106 and the outlet of the fan/blower 108. Thus, the heater tube 106, manifold 110 (FIG. 5), drum 102, and fan 108 of the dryer 100 form part of the open air flow circuit. In accordance with an aspect of the invention, heater tube 106 and fan 108 are known components arranged in the known manner shown in FIGS. 1-3.

In the open air flow circuit, fresh supply air is drawn from within the dryer cabinet 104 into the condenser heat exchanger 154 where the air is warmed through heat exchange with the heated high pressure refrigerant exiting the compressor 152. The warmed air is then further heated as it travels through the heater tube 106, across a single or multiple electrical resistance or gas heating element(s). The air then enters the manifold 110 at the rear side of the dryer 100 (see FIG. 5) and continues into the drum 102 to remove moisture from the laundry inside the drum 102. The warm, moisture laden air is then pulled past a conventional lint filter 112 into the process air fan 108. The air flow is generated by a known type (e.g., centrifugal) fan/blower 108, operating in a suction mode downstream of drum 102. When the air exits the fan 108, the warm, humid air passes through the evaporator heat exchanger 158 before exiting the cabinet 104 of the dryer 100. Thus, as in conventional vented tumble dryers (e.g., dryer 10 of FIG. 1), air flow through the drum 102 is exhausted or vented to outside the cabinet 104. Although not illustrated, provision could be made for recirculating a portion of the exhaust air back to the heater tube 106 and/or condenser heat exchanger 154, to further enhance heat recovery and drying effectiveness. In this case, the take-off for the recirculation could be either upstream or downstream of the evaporator heat exchanger 158.

In an installed orientation, the condenser heat exchanger 154 is stacked on and attached to the evaporator heat exchanger 158 in angularly offset relation. As shown in FIG. 9, the condenser heat exchanger 154 is stacked on top of the evaporator heat exchanger 158. Additionally, as shown, both heat exchangers 154 and 158 are vertically offset or inclined at an angle α with respect to a plane (which as shown has a horizontal orientation). The angle α is nine degrees as shown in FIG. 9, but may be varied, including between 5 and 30 degrees, as a larger angle α results in lower pressure drops for the air flow when entering manifold 110. Other configurations are possible, including, for example, that the heat exchangers 154 and 158 may both be offset at an angle α from a vertical plane, horizontal plane, or other plane, or that the heat exchanger 154 may be vertically offset or inclined at an angle α from the evaporator heat exchanger 158. As a result of the angle of inclination α, the connecting inlet of the heater tube 106 may be positioned at a greater height H1 than the height H2 of the air exhaust portion of the evaporator heat exchanger 158, as illustrated in FIG. 9, and in correspondence to the existing dryer configuration illustrated in FIGS. 1-3. In addition, the outlet of the condenser heat exchanger 154 is elevated relative to the inlet of the same heat exchanger.

Moreover, as shown in FIG. 8, the condenser heat exchanger 154 and the evaporator heat exchanger 158 are horizontally offset (canted) at an angle β with respect to each other. The angle β as shown in FIG. 8 is eleven degrees, but may be between 5 and 30 degrees. Thus, in correspondence to the existing dryer configuration illustrated in FIGS. 1-3, the connecting part of the heater tube 106 and the air exhaust portion of the evaporator 158 may be at different positions P1 and P2 in the horizontal plane as shown in FIG. 8. In addition, the exhaust outlet of the evaporator heat exchanger 158 is offset from its inlet widthwise of the dryer, thus providing correspondence with the exhaust hole and blower outlet locations of an existing dryer configuration as illustrated in FIGS. 1-3. Overall, the configuration permits ready installation of the unit within an existing vented dryer configuration of the type shown in FIGS. 1-3, with minimal required modification.

The offset angles of the heat exchangers 154 and 158 allow the heat pump 150 to readily and compactly fit below the drum 102 within a known vented dryer design and attach to known dryer components (e.g., heater tube 106, blower 108) with minimal modifications. Moreover, the angular offsets and non-parallel air flow through the outlet of each heat exchanger minimize pressure drops in heat pump system 150. For example, the stacked and angled configuration of the heat exchangers 154 and 158 also increases efficiency and decreases pressure drops by avoiding a sharp (e.g., 90 degree) turn for the airflow entering the manifold 110.

Collectively, the casings or housings of the condenser and evaporator heat exchangers 154 and 158 primarily consist of more than one mating piece. For example, in the embodiment illustrated in FIGS. 4-13, the casings or housings of the condenser and evaporator heat exchangers 154 and 158 primarily consist of three clamshell pieces 162, 163, and 164 (see, e.g., exploded view in FIG. 13). The first casing piece 162 mates together with the second casing piece 163, which sits between the condenser 154 and evaporator 158, to enclose the condenser heat exchanger core assembly and create a passage that directs air through the assembly toward the manifold 110 and drum 102. The second casing piece 163 also mates, on its opposite (lower as shown) side, together with the third casing piece 164 to enclose the evaporator heat exchanger core assembly and create a passage that directs air through the assembly and to outside the dryer cabinet 104.

As shown in detail in FIGS. 10, 11, and 13, at least part of the first heat exchanger 154 and second heat exchanger 158 may be supported by one or more component(s) 168, which can be integrated into the casings of the condenser and/or evaporator heat exchangers 154 and 158. The support components 168 serve as a support to hold the condenser 154 and the evaporator 158 heat exchanger units at the proper heights H1 and H2, positions P1 and P2, and angles α and β. As shown in the illustrated embodiment of FIGS. 10, 11, and 13, the support components may be formed in or on the casing pieces 162, 163, and/or 164. Alternatively, support components 168 may be formed as separate components and attached to casing portions 162, 163, and/or 164.

The heat exchanger casing may also support other heat pump subassembly components. For example, as shown in FIGS. 7, 9-10, and 12-13, a support 169 for holding the capillary tube, throttle, or expansion device 156 in place may be formed in or on casing piece 163. Alternatively support 169 may be formed in or on casing pieces 162 or 164. The support component 169 may also be formed as a separate component and attached to casing portion 162, 163, and/or 164.

The heat exchanger casing pieces 162, 163, and/or 164 may also support other components of the heat pump assembly 150 or dryer 100. For example, as shown in FIGS. 5-7 and 10-11, the heat pump subassembly 150 may also include a cooling fan 180. The fan 180 may be mounted near the compressor 152 inside the cabinet 104 of the dryer 100. The fan 180 may be mounted near the compressor 152 with at least one support 182. Support 182 may be formed in or on casing piece 163, as shown in FIGS. 7, 8, 10, and 13. Alternatively, support 182 may be formed in or on casing pieces 162 or 164. The support component 182 may also be formed as a separate component and attached to casing portion 162, 163, and/or 164. The support 182 is configured to orient the cooling fan 180 to cool the upper part of the compressor 152, although other configurations are possible.

The heat exchanger casing may also integrate a reservoir 166. During operation, the evaporator heat exchanger 158 at least partially evaporates refrigerant receiving heat from the air, and the resultant air temperature drop condenses the moisture from the exhaust air stream within heat exchanger 158. The condensed moisture is then collected in reservoir 166 which sits below the evaporator heat exchanger 158. In the embodiment illustrated in FIGS. 4-13, the reservoir 166 is formed as an integral portion of third casing portion 164 (see, e.g., FIG. 13). Alternatively, reservoir 166 may be formed as a separate piece and attached to the casing portion (e.g., 164) that is below the second heat exchanger 158. Other reservoir arrangements and geometries are possible.

The heat pump subassembly 150 may also include a pump 170 to remove condensed water from the reservoir 166. The pump 170 may be seated in the reservoir 166 and secured by a strap or bracket 172 (see, e.g., FIGS. 8 and 9), or otherwise. As condensate water collects in reservoir 166, the pump 170 moves the water to outside the cabinet 104. For example, the pump 170 may pump the water through a tube connected to the pump and an outlet in the rear wall of the cabinet 104. Alternatively, the pump 170 may transfer the collected water to a removable drawer or container within the dryer 100 which the user can then empty periodically. Pump operation may be triggered by a liquid level sensor in a known fashion.

In some embodiments, a refrigerant filter 157 may be placed upstream of the capillary tube 156 to intercept any particles and/or humidity in the refrigerant that can clog the capillary tube. For example, as shown in FIGS. 7 and 12, the dehydrating refrigerant filter 157 is cylindrical in shape and the capillary tube wraps around the cylinder. Other shapes, geometries, and configurations are possible.

Alternative arrangements and configurations of the heat pump components and casing components are possible. For example, FIGS. 14-18 illustrate another embodiment of a dryer 200 with a heat pump subassembly 250 with an alternative casing design and arrangement. Like dryer 100 of FIGS. 4-13, dryer 200 comprises several known elements, including a cabinet 204, rotating drum 202, process air fan 208, heater tube 206, and lint filter 212. As explained above with respect to the heat pump subassembly 150, heat pump subassembly 250 of the dryer 200 also includes a compressor 252, condenser heat exchanger 254, expansion device 256, evaporator heat exchanger 258, and refrigerant tubing/conduits 260. The condenser and evaporator heat exchangers 254 and 258 thermally couple two circuits: a closed loop refrigerant circuit and an open or vented air stream circuit. As with subassembly 150 of FIGS. 4-13, when heat pump subassembly 250 is installed in the dryer 200, it is fitted between the inlet of the heater tube 206 and the outlet of the fan/blower 208.

The condenser heat exchanger 254 and evaporator heat exchanger 258 can have similar construction and positioning as the condenser 154 and evaporator 158 of the heat pump subassembly shown in FIGS. 4-13 and explained in more detail above. For example, the condenser 254 is stacked on and attached to the evaporator heat exchanger 258 as shown, for example, in FIG. 17. Additionally, the condenser heat exchanger 254 is vertically offset or inclined at an angle α with respect to the evaporator heat exchanger 258. As such, the connecting inlet of the heater tube 206 may be positioned at a greater height H1 than the height H2 of the air exhaust portion of the evaporator heat exchanger 258, and in correspondence to the existing dryer configuration illustrated in FIGS. 1-3. In addition, the outlet of the condenser heat exchanger 254 is elevated relative to the inlet of the same heat exchanger. Moreover, as shown in FIG. 16, the condenser heat exchanger 254 and the evaporator heat exchanger 258 are horizontally offset (canted) at an angle β with respect to each other. Thus, in correspondence to the existing dryer configuration illustrated in FIGS. 1-3, the connecting part of the heater tube 206 and the air exhaust portion of the evaporator 258 may be at different positions P1 and P2 in the horizontal plane as shown in FIG. 16.

In the embodiment illustrated in FIGS. 14-18, the casings or housings of the condenser and evaporator heat exchangers primarily consist of four clamshell pieces (see, e.g., exploded view in FIG. 18). Each heat exchanger 254 and 258 has a top and bottom casing portion mated together to enclose the heat exchanger core assembly (convoluted runs of refrigerant conduit and associated heat exchange fins or like elements). Thus, the condenser heat exchanger 254 has a first casing portion 262A and a second casing portion 262B, and the evaporator heat exchanger 258 casing has a first portion 264A and a second portion 264B. As illustrated in, for example, FIG. 18, the first casing portions 262A and 264A may constitute the “top” halves of the cases in an installed position, and the second casing portions 262B and 264B may be the “bottom” halves of the cases. Other arrangements and geometries are possible.

In the embodiment shown in FIGS. 14-18, at least part of the first heat exchanger 254 may be supported by components 268, which can be integrated into the casings of the condenser and/or evaporator heat exchangers 254 and 258. The support components 268 serve as a support for the condenser heat exchanger 254 to hold it at the proper angles α and β with respect to the evaporator 258. As shown in the illustrated embodiment of FIGS. 14-18, the support components may be formed in or on the first casing portion 264A of the evaporator heat exchanger 258 and/or in or on the second casing portion 262B of the condenser heat exchanger 254. Alternatively, support components 268 may be formed as separate components and attached to casing portions 264A and/or 262B.

As shown in FIGS. 14-18, the bottom portion 264B of the evaporator heat exchanger casing may also integrate a reservoir 266 for collecting condensed moisture from the evaporation process. In the embodiment illustrated, the reservoir 266 sits below the evaporator heat exchanger and is formed as an integral portion of the second casing portion 264B. Alternatively, reservoir 266 may be formed as a separate piece and attached to the casing of the second heat exchanger 258. Other reservoir arrangements and geometries are possible. Additionally, a pump 270 may be used to remove condensed water from the reservoir 266 as explained above with respect to pump 170 and reservoir 166 of the embodiment of FIGS. 4-13.

One advantage of a vented heat pump dryer such as dryer 100 or dryer 200 is the ability to incorporate the heating methods of both conventional vented tumble dryers and known closed circuit heat pump dryers. For example, in the dryer 100 with heat pump assembly 150, the conventional electric heater tube 106 is paired with the heat pump 150 so the condenser heat exchanger 154 will serve as a pre-heater for incoming supply air. The combination of the electric heater 106 with the heat pump 150 condenser heat exchanger 154 can reduce overall drying time and limit the required size of the heat pump 150 components. In particular, the size of the compressor 152 and/or condenser 154 can be reduced, since the heat output of the condenser 154 will be supplemented by the electric heater 106. As shown in FIGS. 4-16, the condenser and evaporator heat exchangers 154 and 158 may be approximately the same size, unlike conventional heat pump dryers where the condenser is significantly larger than the evaporator. For example, the evaporator 158 may be 80% to 110% of the volume of the condenser 154. This is possible because the heat exchanger core assemblies within the casings may be identically sized and configured. This gives very significant benefits in the manufacturing. Since the single assembly can be used for either purpose, only one production line and inventory are required, rather than two, and there is no need for discrimination between confusingly similar parts. Moreover, the use of both the conventional heater tube 106 and the condenser heat exchanger 154 to heat incoming air can reduce the necessary air flow rate, improve overall performance, especially in terms of drying time and avoid the need for significant modification to the fan/blower 108. The machine can be switched between an ECO mode (heat pump only) or FAST mode (heat pump+heater at high average power).

The vented dryer 100 with heat pump subassembly 150 also limits the adverse impact of sensible cooling and heat exchange on the overall efficiency of the dryer 100. In a conventional heat pump dryer with a closed air stream circuit, it is necessary to remove moisture from the air because the same air must be recirculated. Thus, the warm humid air exiting the drum passes over the evaporator to condense the retained moisture before passing over the condenser to be heated again. The air in the evaporator exchanges both latent heat (to condense the retained moisture) and sensible heat (cooling of the air which represents a drawback). As a result, the temperature of the coolant at the evaporator must be kept very low, for example, below the dew point, and the condenser must give back the energy (heat) lost to the sensible cooling before being able to heat the air to the usual temperature. However, in dryer 100, the open, vented air flow loop minimizes the necessary latent and/or sensible heat exchanged in the evaporator 158 which allows the air at the inlet of the condenser heat exchanger 154 to be at a higher temperature (e.g., ambient temperature) and pressure. As a result, the condenser 154 (and the following heater tube 106) does not need to overcome sensible cooling to heat the air to the appropriate temperature for drying laundry within the drum 102.

The heat pump subassembly 150 may be integrated within a conventional vented tumble dryer with few modifications to the existing structure. This could be done at the time of manufacture or as a modular retrofit to an existing appliance, e.g., a known tumble dryer 10 as shown in FIGS. 1-3. For example, the heat exchange subassembly 150, including a compressor, condenser heat exchanger, expansion device, evaporator heat exchanger, and refrigerant tubes, may replace the conventional supply tube 14 and exhaust tube 20 (FIGS. 1-3), and be fitted onto the heater tube 106 on one end and the outlet of the fan/blower 108 on the other with only minor modifications to existing components.

Alternatively, the inventive aspects of the present invention, including at least the casing designs and modular aspects of the heat pump subassemblies 150 and 250, may be applied to and incorporated into condenser dryers.

The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. 

1. A vented laundry dryer comprising: a drying chamber; a process air fan downstream of the drying chamber for drawing air through the drying chamber; and a heat pump system comprising a condenser heat exchanger unit enclosed by separately formed and mated together first and second casing portions and an evaporator heat exchanger unit enclosed by the second casing portion mated together with a separately formed third casing portion; wherein the condenser and evaporator heat exchanger units are stacked one on top of the other, said condenser heat exchanger unit connecting to a manifold upstream the drying chamber so that process air is drawn through the condenser heat exchanger unit before entering said drying chamber, and said evaporator heat exchanger unit connecting to an air outlet of said process air fan so that process air is passed through the evaporator heat exchanger unit before being exhausted from the dryer; and wherein the heat pump system further comprises a coolant circuit comprising a coolant fluid expansion device and a compressor.
 2. The vented laundry dryer of claim 1 further comprising a heater positioned upstream of the manifold for heating air passing therethrough, said condenser heat exchanger unit connecting to an air inlet of said heater.
 3. The vented laundry dryer of claim 1 wherein the third casing portion is at least in part below the evaporator heat exchanger unit and further comprises a water condensate reservoir.
 4. The vented laundry dryer of claim 3 further comprising a water pump arranged to expel water condensate from said reservoir.
 5. The vented laundry dryer of claim 1 wherein the condenser and evaporator heat exchanger units comprise substantially identical heat exchanger core assemblies.
 6. The vented laundry dryer of claim 5 wherein the heat exchanger core assemblies each have a generally rectangular box shape.
 7. The vented laundry dryer of claim 1 wherein the condenser heat exchanger unit is angularly offset with respect to the evaporator heat exchanger unit.
 8. The vented laundry dryer of claim 1 wherein the condenser heat exchanger unit is angularly offset with respect to the evaporator heat exchanger unit in a horizontal plane.
 9. The vented laundry dryer of claim 1 wherein the condenser heat exchanger unit is angularly offset with respect to the evaporator heat exchanger unit in a vertical plane.
 10. The vented laundry dryer of claim 1 wherein the condenser and evaporator heat exchanger units are angularly offset relative to each other in both a horizontal plane and a vertical plane.
 11. The vented laundry dryer of claim 1 wherein the condenser and evaporator heat exchanger units are attached to each other in parallel in a plane angularly offset with respect to a vertical plane.
 12. The vented laundry dryer of claim 1 further comprising at least one support structure serving to attach a portion of the coolant circuit to one of the first, second, or third casing portions.
 13. The vented laundry dryer of claim 1 further comprising a cooling fan for the compressor, wherein the cooling fan is attached to at least one of the first, second, or third casing portions by an intermediate support structure.
 14. The vented laundry dryer of claim 1 wherein the second and third casing portions form an inlet configured to connect to the outlet of the process air fan.
 15. A heat pump subassembly for a dryer with a process air fan, and a drum, the heat pump subassembly comprising: a condenser heat exchanger unit having an air inlet and outlet; and an evaporator heat exchanger unit having an air inlet and outlet; wherein said condenser heat exchanger unit comprises a condenser heat exchanger core assembly enclosed in a first casing portion and a second casing portion, and wherein the evaporator heat exchanger unit comprises an evaporator heat exchanger core assembly enclosed by the second casing portion and a third casing portion; and wherein the first, second, and third casing portions are configured to stack the condenser and evaporator heat exchanger core assemblies one on top of the other.
 16. The heat pump subassembly of claim 15 wherein the first, second, and third casing portions are configured to orient the condenser and evaporator heat exchanger core assemblies in an angularly offset relation
 17. The heat pump subassembly of claim 15, further comprising a heater, wherein the air outlet of the condenser heat exchanger unit is adapted for connection to an inlet of said heater.
 18. The heat pump subassembly of claim 15, wherein each of said first, second, and third casing portions comprise separately formed sections.
 19. The heat pump subassembly of claim 18 wherein the first and second casing portions are mated together, and the second and third portions are mated together.
 20. The heat pump subassembly of claim 15 wherein the third casing portion further comprises a condensate reservoir.
 21. The heat pump subassembly of claim 20 further comprising a water pump arranged to expel water condensate from the reservoir.
 22. The heat pump subassembly of claim 15 further comprising an expansion device, wherein at least part of the expansion device is supported within the dryer by a support component attached to at least one of the first, second, or third casing portions.
 23. The heat pump subassembly of claim 22 wherein at least a portion of the support component is formed integral with one of the first, second, or third casing portions.
 24. The heat pump subassembly of claim 15 further comprising: a compressor; a cooling fan for said compressor; and at least one support component, wherein at least part of the cooling fan is supported by the support component and wherein the support component attaches the cooling fan to at least one of the first, second, or third casing portions.
 25. The heat pump subassembly of claim 24 wherein at least a portion of the support component is formed integral with one of the first, second, or third casing portions. 